This application is based on application No. H11-194980 filed in Japan, the entire content of which is hereby incorporated by reference.
1. Field of the Invention
The present invention pertains to an image forming system comprising an image forming apparatus that, when a paper jam occurs in the original document or recording sheet conveying system and the problem is eliminated, re-forms the images that were not properly formed due to the paper jam, and to a finisher that performs finishing processes on the recording sheets ejected from the image forming apparatus.
2. Description of the Related Art
In recent years, in response to increasing user demand, manufacturers of image forming apparatuses such as copying machines and printers have gone beyond simply forming and outputting images on recording sheets, and are often providing, as optional devices to be attached to the image forming apparatuses, devices (hereinafter collectively termed xe2x80x98finishersxe2x80x99) that perform finishing processes to the recording sheets, such as folding of the sheets on which images have been formed into two parts or three parts (z-folding) (hereinafter termed the xe2x80x98paper folding processxe2x80x99), the punching of holes at prescribed locations on the sheets (hereinafter termed the xe2x80x98punching processxe2x80x99) or the binding of the sheets using staples (hereinafter termed the xe2x80x98stapling processxe2x80x99).
In these finishers, in order to perform stapling, for example, the sheets that were sequentially ejected from the image forming apparatus must be stacked, and after a prescribed number of sheets have been stacked, stapling must be performed. Therefore, the finisher is often equipped with a stacking means such as a finishing tray on which sheets that have undergone image formation are stacked.
On the other hand, many recent image forming apparatuses include a function that performs jam correction when a paper jam (hereinafter simply termed xe2x80x98jamxe2x80x99) involving the recording sheets on which images are formed occurs in the conveyance system. Here, jam correction refers to the function in which image formation is performed anew for the images which were not properly formed due to the occurrence of the jam, using the image data stored in the image memory.
In this jam correction, the effect of the jam is compensated for and consequently all of the images are formed by counting the number of pages of the original document for which image formation should be performed and the number of pages for which image formation has been properly completed, and when a paper jam is eliminated, image formation is performed anew for those pages of the original document for which image formation has not yet been properly completed.
In a conventional image forming system comprising an image forming apparatus having the jam correction function described above and a conventional finisher, even if a jam occurs in the image forming apparatus, no special processes take place in the finisher. In addition, regarding the recording sheets that have been ejected to the finisher, the image forming apparatus simply assumes that image formation has properly been performed on them and that they have been ejected.
However, when a jam occurs in the image forming apparatus of a conventional image forming system, when the user tries to eliminate the problem, there are cases in which the user removes the sheets that are remaining on the stacking means, such as a finishing tray, inside the finisher. In such a case, in a conventional image forming system, image formation is not performed again for the images that were already formed on the sheets removed from the stacking means, and as a result, the problem occurs that the bundle of stapled sheets has missing pages.
The object of the present invention is to resolve the problem described above.
Another object of the present invention is to provide an image forming system in which the bundle of sheets on which images have been formed, does not have missing pages even when the user removes the recording sheets remaining on the stacking means in order to carry out jam correction.
These and other objects of the present invention are attained by an image forming apparatus comprising: an image forming unit for receiving a job comprising multiple pages and sequentially performing image formation; a tray for receiving sheets on which images have been formed by the image forming unit; a counter that counts the number of sheets received by the tray; a first controller that, when a jam occurs in the image forming unit during the job and image formation is subsequently restarted, if sheets are remaining on the tray, restarts image formation with the page corresponding to the count value of the counter; and a second controller that, when a jam occurs in the image forming unit during the job and image formation is subsequently restarted, if sheets are not remaining on the tray, restarts image formation with the first page regardless of the count value.
These and other objects of the present invention are also attained by an image forming apparatus comprising: an image forming unit for forming images on sheets by performing multiple image forming operations; a first counter for counting the commencement of the image forming operations; a holder for holding the sheets ejected from the image forming unit; a finisher for performing finishing processes to the sheets stacked on the holder; a second counter for counting the sheets held on the holder; a sensor for detecting whether or not sheets are stacked on the holder; and a controller for controlling the image forming unit so that where the sensor detects that sheets are stacked on the holder after the jam that occurred in the image forming unit is eliminated, the image forming unit restarts image formation for the number or sheets counted by the first counter but not by the second counter, and where the sensor detects that no sheets are stacked on the holder, the image forming unit restarts image formation for the number of sheets counted by the first counter regardless of the count value of the second counter.
These and other objects of the present invention are also attained by an image forming system comprising: a finisher having: a finishing device for performing a finishing process on the bundle of sheets on which images have been formed and that are stacked on the tray; and a removing mechanism for removing from the tray the bundle of sheets that have undergone the finishing process by the finishing device; and an image forming apparatus for re-forming images that were formed on the bundle of sheets removed from the tray by a means other than the removing mechanism.
These and other objects of the present invention are also attained by an image forming system comprising an image forming apparatus having a function in which, when a paper jam occurs in the original document conveyance system or in recording sheet conveyance system and is subsequently eliminated, the images that were not properly formed due to the paper jam are formed again, and a finisher having a tray on which the recording sheets ejected from the image forming apparatus are stacked and for performing a finishing process to the recording sheets, said system comprising: a first counter for counting the number of the original document pages on which an image should be formed by means of the image forming apparatus; a second counter for counting the number of recording sheets stacked on the stacking means; a calculator that, when a paper jam is eliminated, calculates the number of images that should be formed again by subtracting the count value of the second counter from the count value of the first counter; a determining for determining whether or not recording sheets are stacked on the tray before the calculation by means of the calculator takes place; and a controller that, where it is determined by the determining unit that no recording sheets are stacked on the tray, sets the count value of the second counter to zero and prompts the calculation by the calculator.
These and other objects of the present invention are also attained by a finisher having a tray on which the recording sheets ejected from the image forming apparatus are stacked, said finisher also having: a first sensor that detects the stacking of a recording sheet on the tray and generates a signal representing the number of sheets on the tray; and a second sensor that, when a paper jam occurs in the original document or recording sheet conveyance system of the image forming apparatus and is subsequently eliminated, detects whether or not recording sheets are stacked on the tray, and generates a signal representing the detection result.
These and other objects of the present invention are also attained by a finisher comprising: a tray on which the recording sheets ejected from an image forming apparatus are stacked; a first sensor that detects the stacking of a recording sheet on the tray and generates a signal representing the number of sheets on the tray; and a second sensor that, when a paper jam occurs in a original document conveyance system or in a recording sheet conveyance system of the image forming apparatus and is subsequently eliminated, detects whether or not recording sheets are stacked on the tray, and generates a signal representing the detection result.
These and other objects of the present invention are also attained by an image forming system comprising an image forming apparatus having a function by which, when a paper jam occurs in the original document or recording sheet conveyance system and is subsequently eliminated, the images that were not properly formed due to the problem are formed again, as well as a finisher that has a stacking means on which the recording sheets ejected from the image forming apparatus are stacked, wherein, when forming images that were not properly formed due to a paper jam, said image forming apparatus determines the number of images that should be formed again based on the information provided by the finisher regarding the number of images that should be formed again.
These and other objects of the present invention are also attained by an image forming method comprising: a step in which multiple images are sequentially formed by the image forming apparatus on multiple sheets, which are then ejected outside the apparatus; a step in which the sheets ejected from the image forming apparatus are sequentially held on the first holder; a step in which a finishing process is performed to the sheets held on the first holder; a step in which, when a paper jam occurs in the image forming apparatus, it is determined whether or not the sheets are stacked on the first holder; a step in which, when the paper jam is eliminated, the first image of the images to be sequentially formed is determined based on the sensor output; and a step in which image formation is performed again in response to the determination.
The invention itself, together with further objects and attendant advantages, will best be understood by reference to the following detailed description taken in conjunction with the accompanying drawings.